Properties and Reactions of Singlet Dioxygen

Foote, Christopher S.; Clennan, Edward L.

doi:10.1007/978-94-007-0874-7_4

Cited by 182 publications

(184 citation statements)

References 95 publications

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“…The first is photooxidation (35,36). Triplet organic molecules react with ground-state molecular oxygen in a triplet-triplet annihilation process, yielding excited singlet oxygen and the ground-state organic molecule.…”

Section: Photophysics and Photochemistry In Single-molecule Measurementsmentioning

confidence: 99%

Optical Studies of Single Molecules at Room Temperature

Xie

Trautman²

1998

Annu. Rev. Phys. Chem.

642

551

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Recent developments in optical studies of single molecules at room temperature are reviewed, with an emphasis on the underlying principles and the potential of single-molecule experiments. Examples of single-molecule studies are given, including photophysics and photochemistry pertinent to single-molecule measurements, spectral fluctuations, Raman spectroscopy, diffusional motions, conformational dynamics, fluorescence resonant energy transfer, exciton dynamics, and enzymatic turnovers. These studies illustrate the information obtainable with the single-molecule approach that is hidden in ensemble-averaged measurements.

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Section: Photophysics and Photochemistry In Single-molecule Measurementsmentioning

confidence: 99%

Optical Studies of Single Molecules at Room Temperature

Xie

Trautman²

1998

Annu. Rev. Phys. Chem.

642

551

View full text Add to dashboard Cite

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Section: Introductionmentioning

confidence: 99%

“…[1][2][3] It is wellestablished that singlet oxygen is an oxidizing/oxygenating agent for a wide range of organic molecules. 1,4 Production of sufficient quantities of singlet oxygen in a biological environment can perturb cellular processes, and can ultimately cause cell death via apoptosis or necrosis. 5,6 The cytotoxic effect of singlet oxygen is currently used in clinical practice in a treatment modality called Photodynamic Therapy, PDT, whereby the controlled production of singlet oxygen leads to the eradication of undesired tissue.…”

Section: Introductionmentioning

confidence: 99%

Singlet Oxygen in a Cell: Spatially Dependent Lifetimes and Quenching Rate Constants

2008

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Singlet molecular oxygen, O 2 (a 1 ∆ g ), can be created in a single cell from ground state oxygen, O 2 (X 3 Σ g -), upon focused laser irradiation of an intracellular sensitizer. This cytotoxic species can subsequently be detected by its 1270 nm phosphorescence (a 1 ∆ g → X 3 Σ g -) with subcellular spatial resolution. The singlet oxygen lifetime determines its diffusion distance and, hence, the intracellular volume element in which singlet-oxygen-initiated perturbation of the cell occurs. In this study, the time-resolved phosphorescence of singlet oxygen produced by the sensitizers chlorin (Chl) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) was monitored. These molecules localize in different domains of a living cell. The data indicate that (i) the singlet oxygen lifetime and (ii) the rate constant for singlet oxygen quenching by added NaN 3 depend on whether Chl or TMPyP was the photosensitizer.These observations likely reflect differences in the chemical and physical constituency of a given subcellular domain (e.g., spatially-dependent oxygen and NaN 3 diffusion coefficients) and, as such, are evidence that singlet oxygen responds to the inherent heterogeneity of a cell.Thus, despite a relatively long intracellular lifetime, singlet oxygen does not diffuse a great distance from its site of production. This is a consequence of an apparent intracellular viscosity that is comparatively large.3

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“…Singlet oxygen has been proven to be genotoxic (Epe, 1991) and mutagenic (Ouchane et al, 1997). Its half-life ranges from 4 ms in water (Foote & Clennan, 1995) to 200 ns in living cells (Gorman & Rodgers, 1992). Diffusion of singlet oxygen is limited to a range of 10 nm in vivo (Sies & Menck, 1992) and 100 nm in aqueous solutions (Kochevar & Redmond, 2000).…”

Section: Introductionmentioning

confidence: 99%

Photo-oxidative stress in Rhodobacter sphaeroides: protective role of carotenoids and expression of selected genes

2005

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In Rhodobacter sphaeroides, carotenoids are essential constituents of the photosynthetic apparatus and are assumed to prevent the formation of singlet oxygen by quenching of triplet bacteriochlorophyll a (BChl a) in vivo. It was shown that small amounts of singlet oxygen are generated in vivo by incubation of R. sphaeroides under high light conditions. However, growth and survival rates were not affected. Higher amounts of singlet oxygen were generated by BChl a in a carotenoid-deficient strain and led to a decrease in growth and survival rates. The data support earlier results on the pivotal role of carotenoids in the defence against stress caused by singlet oxygen. Results obtained under photo-oxidative stress conditions with strains impaired in carotenoid synthesis suggest that sphaeroidene and neurosporene provide less protection against methylene-blue-generated singlet oxygen than sphaeroidenone in vivo. Despite their protective function against singlet oxygen, relative amounts of carotenoids did not accumulate in R. sphaeroides wild-type cultures under photo-oxidative stress, and relative mRNA levels of phytoene dehydrogenase and sphaeroidene monooxygenase did not increase. In contrast, singlet oxygen specifically induced the expression of glutathione peroxidase and a putative Zn-dependent hydrolase, but mRNA levels of hydrogen-peroxide-degrading catalase E were not significantly affected by photo-oxidative stress. Based on these results, it is suggested that singlet oxygen acts as a specific signal for gene expression in R. sphaeroides. Presumably transcriptional regulators exist to specifically induce the expression of genes involved in the response to stress caused by singlet oxygen.

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Properties and Reactions of Singlet Dioxygen

Cited by 182 publications

References 95 publications

Optical Studies of Single Molecules at Room Temperature

Optical Studies of Single Molecules at Room Temperature

Singlet Oxygen in a Cell: Spatially Dependent Lifetimes and Quenching Rate Constants

Photo-oxidative stress in Rhodobacter sphaeroides: protective role of carotenoids and expression of selected genes

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